Three dimensional sensors, systems, and associated methods

ABSTRACT

3D sensors, systems, and associated methods are provided. In one aspect, for example, a monolithic 3D sensor for detecting infrared and visible light can include a semiconductor substrate having a device surface, at least one visible light photodiode formed at the device surface and at least one 3D photodiode formed at the device surface in proximity to the at least one visible light photodiode. The device can further include a quantum efficiency enhanced infrared light region functionally coupled to the at least one 3D photodiode and positioned to interact with electromagnetic radiation. In one aspect, the quantum efficiency enhanced infrared light region is a textured region located at the device surface.

PRIORITY DATA

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/451,510, filed on Mar. 10, 2011, which isincorporated herein by reference.

BACKGROUND

The interaction of light with semiconductor devices is at the core ofmany important innovations. Semiconductor photodetecting devices, suchas photovoltaics, photodiodes, imagers, are used in various technologiesfor example, solar cells, digital cameras, optical mice, video cameras,video game consoles, cell phones, and the like. Silicon is the mostprevalent semiconductor for electronic devices, and is also very widelyused for optoelectronic devices such as optical detectors, image sensorsand solar cells. The bandgap of silicon at room temperature is 1.12 eV,and in general semiconductors do not absorb photons that have energiesbelow their bandgap energy. However, there are many applications thatrequire optical detection at lower energy levels than silicon's bandgap.Of particular interest, for example, are the energy levels 0.95 eV (1310nm) and 0.8 eV (1550 nm). These applications are typically served byother semiconductors with smaller bandgaps, such as germanium, indiumgallium arsenide, mercury cadmium telluride and the like.

SUMMARY

The present disclosure provides 3D sensors, systems, and associatedmethods. In one aspect, for example, a monolithic 3D sensor capable ofdetecting infrared and visible light is provided. Such a device caninclude a semiconductor substrate having a device surface, at least onevisible light photodiode formed at the device surface and at least one3D photodiode formed at the device surface in proximity to the at leastone visible light photodiode. The device can further include a quantumefficiency enhanced infrared light region functionally coupled to the atleast one 3D photodiode and positioned to interact with electromagneticradiation. In one aspect, the quantum efficiency enhanced infrared lightregion is a textured region located at the device surface. In anotheraspect, the quantum efficiency enhanced infrared light region hassurface structures formed using a pulsed laser with a pulse duration offrom about 1 femtosecond to about 500 picoseconds. In yet anotheraspect, the surface structures have an average height of from about 5 nmto about 500 μm.

Various photodiode combinations are contemplated, and any suchcombination of visible light photodiodes and 3D photodiodes isconsidered to be within the present scope. In one aspect, for example,the at least one visible light photodiode includes at least one redlight-sensitive photodiode, at least one blue light-sensitivephotodiode, at least one green light-sensitive photodiode, and at leasttwo 3D photodiodes. In another aspect, the 3D photodiode is operable todetect infrared light having a wavelength of greater than about 800 nm.In yet another aspect, the device can further include an infrared narrowbandpass filter optically coupled to the 3D photodiode and positioned tofilter electromagnetic radiation impinging on the 3D photodiode. In afurther aspect, the device can include an infrared cut filter opticallycoupled to the at least one visible light diode and positioned to filterinfrared electromagnetic radiation impinging on the at least one visiblelight photodiode.

The design of the 3D photodiode can vary depending on the desiredfunctionality of the sensor. In one aspect, for example, the 3Dphotodiode further includes circuitry for capturing signals generated bythe 3D photodiode in response to detection of a pulse of infrared lightfrom an infrared light source. In another aspect, the 3D photodiodefurther includes circuitry for calculating time of flight information.In yet another aspect, the device further includes circuitry forsynchronizing light capture of the 3D photodiode with an infrared lightsource. In a further aspect, the device can include readout circuitryfunctionally coupled to the at least one visible light photodiode andthe at least one 3D photodiode operable to function in global shuttermode.

The present disclosure additionally provides systems for detectinginfrared and visible light. In one aspect, such a system can include amonolithic 3D sensor for detecting infrared and visible light, wheresuch a monolithic sensor further includes a semiconductor substratehaving a device surface, at least one visible light photodiode formed atthe device surface, at least one 3D photodiode formed at the devicesurface in proximity to the at least one visible light photodiode, and aquantum efficiency enhanced infrared light region functionally coupledto the at least one 3D photodiode and positioned to interact withelectromagnetic radiation. The system can also include an infrared lightsource operable to emit infrared light detectable by the 3D photodiode,and synchronization circuitry between the infrared light source and the3D photodiode to synchronize detection of infrared light 3D photodiodewith a pulse of the infrared light source.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantage of the presentdisclosure, reference is made to the following detailed description ofembodiments herein in connection with the accompanying drawings, inwhich:

FIG. 1 illustrates basic principles of time of flight (TOF);

FIG. 2 is cross section view of a monolithic sensor in accordance withone aspect of the present disclosure;

FIG. 3 is an illustration of a pixel arrangement scheme in accordancewith one aspect of the present disclosure;

FIG. 4 is an illustration of a pixel arrangement scheme in accordancewith one aspect of the present disclosure;

FIG. 5 is an illustration of a pixel arrangement scheme in accordancewith one aspect of the present disclosure;

FIG. 6 is an illustration of a pixel arrangement scheme in accordancewith one aspect of the present disclosure;

FIG. 7 is a timing schematic of basic TOF CMOS pixel operationprinciples in accordance with one aspect of the present disclosure;

FIG. 8 is a cross-sectional view of a 3D TOF pixel and a visible (RGB)pixel in accordance with one aspect of the present disclosure;

FIG. 9 is a schematic of a 6-transistor global shutter visible (RGB)pixel in accordance with one aspect of the present disclosure;

FIG. 10 is a timing diagram for a visible 6T global shutter pixel inaccordance with one aspect of the present disclosure;

FIG. 11 is a schematic diagram for a 3D TOF global shutter CMOS pixel inaccordance with one aspect of the present disclosure;

FIG. 12 is a timing diagram for 3D TOF pixel array in accordance withone aspect of the present disclosure;

FIG. 13 is a timing diagram for a 3D TOF pixel array during backgroundsignal extraction in accordance with one aspect of the presentdisclosure;

FIG. 14 is cross section view of a system including monolithic sensor inaccordance with one aspect of the present disclosure; and

FIG. 15 is a graphical representation of a standard imager compared to aquantum efficiency enhanced imager in accordance with one aspect of thepresent disclosure.

DETAILED DESCRIPTION

Before the present disclosure is described herein, it is to beunderstood that this disclosure is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting.

DEFINITIONS

The following terminology will be used in accordance with thedefinitions set forth below.

It should be noted that, as used in this specification and the appendedclaims, the singular forms “a,” and, “the” can include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a dopant” can include one or more of such dopants andreference to “the layer” can include reference to one or more of suchlayers.

As used herein, the terms “light” and “electromagnetic radiation” can beused interchangeably and can refer to light or electromagnetic radiationin the ultraviolet, visible, near infrared, and infrared spectra. Theterms can further more broadly include electromagnetic radiation such asradio waves, microwaves, x-rays, and gamma rays. Thus, the term “light”is not limited to electromagnetic radiation in the visible spectrum.Many examples of light described herein refer specifically toelectromagnetic radiation in the visible and infrared (and/or nearinfrared) spectra. For purposes of this disclosure, visible rangewavelengths are considered to be from approximately 350 nm to 800 nm andnon-visible wavelengths are longer than about 800 nm or shorter thanabout 350 nm. The infrared spectrum includes a near infrared portion ofthe spectrum including wavelengths of approximately 800 to 1100 nm, ashort wave infrared portion of the spectrum including wavelengths ofapproximately 1100 nm to 3 micrometers, and a mid to long wave infrared(or thermal infrared) portion of the spectrum including wavelengthsgreater than about 3 micrometers up to about 30 micrometers. These aregenerally and collectively referred to herein as “infrared” portions ofthe electromagnetic spectrum unless otherwise noted.

As used herein, “quantum efficiency” (QE) is defined as the percentageof photons incident on an optoelectronic device that are converted intoelectrons. External QE (EQE) is defined as the current obtained outsideof the device per incoming photon. As such, EQE therefore depends onboth the absorption of photons and the collection of charges. The EQE islower than the QE due to recombination effects and optical losses (e.g.transmission and reflection losses).

As used herein, the terms “3D” and “three dimensional” can be usedinterchangeably, and refer to obtaining distance information fromelectromagnetic radiation.

As used herein, the terms “disordered surface” and “textured surface”can be used interchangeably, and refer to a surface having a topologywith nano- to micron-sized surface variations. Such a surface topologycan be formed by the irradiation of a laser pulse or laser pulses,chemical etching, lithographic patterning, interference of multiplesimultaneous laser pulses, or reactive ion etching. While thecharacteristics of such a surface can be variable depending on thematerials and techniques employed, in one aspect such a surface can beseveral hundred nanometers thick and made up of nanocrystallites (e.g.from about 10 to about 50 nanometers) and nanopores. In another aspect,such a surface can include micron-sized structures (e.g. about 1 μm toabout 60 μm). In yet another aspect, the surface can include nano-sizedand/or micron-sized structures from about 5 nm and about 500 μm. Avariety of techniques can be utilized to measure the size of suchstructures. For example, for cone-like structures the above ranges areintended to be measured from the peak of a structure to the valleyformed between that structure and an adjacent neighboring structure. Forstructures such as nanopores, the above ranges are intended to beapproximate diameters. Additionally, the surface structures can bespaced at various average distances from one another. In one aspect,neighboring structures can be spaced at a distance of from about 50 nmto about 50 μm from. In another aspect, neighboring structures can bespaced at a distance of from about 50 nm to about 2 μm from. Suchspacing is intended to be from a center point of one structure to thecenter point of a neighboring structure.

As used herein, the term “fluence” refers to the amount of energy from asingle pulse of laser radiation that passes through a unit area. Inother words, “fluence” can be described as the energy density of onelaser pulse.

As used herein, the terms “surface modifying” and “surface modification”refer to the altering of a surface of a semiconductor material usinglaser irradiation, chemical etching, reactive ion etching, lithographicpatterning, etc. In one specific aspect, surface modification caninclude processes using primarily laser radiation or laser radiation incombination with a dopant, whereby the laser radiation facilitates theincorporation of the dopant into a surface of the semiconductormaterial. Accordingly, in one aspect surface modification includesdoping of a semiconductor material.

As used herein, the term “target region” refers to an area of asemiconductor material that is intended to be doped or surface modified.The target region of a semiconductor material can vary as the surfacemodifying process progresses. For example, after a first target regionis doped or surface modified, a second target region may be selected onthe same semiconductor material.

As used herein, the term “monolithic” refers to an electronic device inwhich electronic components are formed on the same substrate. Forexample, two monolithic pixel elements are pixel elements that areformed on the same semiconductor substrate.

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given value may be “alittle above” or “a little below” the endpoint.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity, and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to include allthe individual numerical values or sub-ranges encompassed within thatrange as if each numerical value and sub-range is explicitly recited. Asan illustration, a numerical range of “about 1 to about 5” should beinterpreted to include not only the explicitly recited values of about 1to about 5, but also include individual values and sub-ranges within theindicated range. Thus, included in this numerical range are individualvalues such as 2, 3, and 4 and sub-ranges such as from 1-3, from 2-4,and from 3-5, etc., as well as 1, 2, 3, 4, and 5, individually.

This same principle applies to ranges reciting only one numerical valueas a minimum or a maximum. Furthermore, such an interpretation shouldapply regardless of the breadth of the range or the characteristicsbeing described.

The Disclosure

The following disclosure relates to photosensitive diodes, pixels, andimagers capable of detecting visible light as well as infrared lightutilized to provide depth information (i.e. 3D information), includingassociated methods of making such devices. Such device additionallyexhibit enhanced absorption and quantum efficiencies. In one aspect, forexample, such a 3D imaging device can include at least one firstsemiconductor pixel, at least one second semiconductor pixel, at leastone third semiconductor pixel, and at least one 3D semiconductor pixelthat is capable of detecting the distance of an object. This 3D pixelcan be monolithically arranged with the other semiconductor pixels. Thefirst, second, third, and 3D semiconductor pixels can be configured todetect light having a first, second, third and fourth wavelength,respectively. Further the first wavelength can be in the range of about400 nm to about 500 nm; the second wavelength in the range of about 500nm to about 550 nm; the third wavelength in the range of about 550 nm toabout 700 nm and the fourth wavelength in the range of about 700 nm toabout 1200 nm. In some aspects, a monolithic sensor can include multiple3D pixels operable to detect different wavelengths. For example,different 3D pixels can be tuned to specific wavelengths such as, forexample, 850 nm, 960 nm, 1064 nm, etc. It can also be beneficial toinclude multiple 3D pixels operable to detect the same wavelength. Asone non-limiting example, a monolithic sensor could include multiple 3Dpixels operable to detect at 1064 nm and multiple 3D pixels operable todetect at 960. It should be understood that various arrangements andcombinations of pixel types and pixel numbers are contemplated, and anysuch combination is considered to be within the present scope.

In one embodiment, the 3D semiconductor pixel can include asemiconductor substrate, a semiconductor layer formed at or from thesemiconductor substrate, and a quantum efficiency enhanced infraredlight region associated with the semiconductor layer. In one aspect, thequantum efficiency enhanced infrared light region can be a texturedregion. In another aspect, the semiconductor substrate and thesemiconductor layer are comprised of silicon.

There are many applications that utilize depth information, non-limitingexamples of which can include hands-free gesture control, video games,medical applications, machine vision, and the like. Time-of-flight (TOF)is one exemplary method of determining depth information that has beendeveloped for use in radar and LIDAR (Light Detection and Ranging)systems. The basic principle of TOF involves sending a signal andmeasuring a property of the returned signal from a target. The measuredproperty is used to determine the TOF. The distance is derived bymultiplication of half the TOF and the velocity of the signal in theapplication medium.

FIG. 1 shows an illustration of generalized TOF measurement with atarget having multiple surfaces that are separated spatially. Equation Ishows one example of how such distance measurements can be calculated.

$\begin{matrix}{d = \frac{{TOF}*c}{2}} & I\end{matrix}$

Where d is the distance measurement and c is the speed of light. Bymeasuring the time (e.g. TOF) that it takes light 102 to travel to andfrom a target 104, the distance between a light emitting diode (LED) andthe surface of the target can be derived. For an imager, if each pixelcan perform the above TOF measurement, for a given lens system, abeneficial 3D image of the target can be achieved. Since, the speed oflight in a vacuum is 3e⁸ msec, light traveling at that speed will reacha target at 30 cm in a nanosecond. Thus, distance measurements can bedifficult with TOF methods when the target is relatively near thesource, which is often the case for many 3D imaging applications. Onenon-limiting example of a method for TOF measurement to overcome thisissue utilizes a modulated light pulse and measure the phase delaybetween emitted light and received light. Based on the phase delay andpulse width, the TOF can be derived. Such a light pulse can be emittedfrom, for example, an LED light source.

Furthermore, many current pixels or imagers are manufactured on asilicon material that has been epitaxially (EPI) grown. Most epitaxiallygrown silicon is relatively thin (e.g. less than 30 μm) and is thuslimited on the amount of infrared electromagnetic radiation that thematerial can absorb/detect, rendering pixel quantum efficiency aroundnear infrared and infrared wavelengths poor. To achieve acceptablesignal to noise ratio for such devices, high power LED are needed togenerate the infrared signal. Without such higher powered LEDs, thepotentially measureable distance range is very short, and resultinghigher electrical crosstalk can significantly affect the spatialresolution of the depth map. Conversely, if the EPI thickness isincreased in such a pixel, the infrared quantum efficiency can beincreased, although not to acceptable levels for many applications.Increasing the EPI thickness, however, can significantly slow electronmigration and degradation on demodulation performance. This can resultin poor depth accuracy or in other words, an increase in depth noise.Pixels according to aspects of the present disclosure overcome problemsthat have previously been associated with depth measurements. Forexample, in one aspect, such a device can utilize a silicon EPI layerhaving a thickness of from about 2 μm to about 5 μm that can achievehigh QE in infrared wavelengths.

In one exemplary aspect, as is shown in FIG. 2, a monolithic 3D sensorfor detecting infrared and visible light is provided. Such a sensor caninclude a semiconductor substrate 202 having a device surface 204, atleast one visible light photodiode 206 formed at or from the devicesurface 204, and at least one 3D photodiode 208 formed at or from thedevice surface 204 in proximity to the at least one visible lightphotodiode 206. Thus the photodiodes in the sensor can be arrangedmonolithically with respect to one another. The monolithic 3D sensor canalso include a quantum efficiency enhanced infrared light region 210functionally coupled to the at least one 3D photodiode 208 andpositioned to interact with electromagnetic radiation. It should benoted that, in some aspects, various layers can separate the quantumefficiency enhanced infrared light region and the 3D photodiode,including, but not limited to, an oxide layer. Thus, the 3D photodiodehas enhanced responsivity and/or detectability in the infrared regionsof the light spectrum. It is noted that the device surface can be aportion of the semiconductor substrate, or the device surface can be anadditional layer, such as an epitaxially grown layer, that is formed onthe substrate.

In some aspects, the at least one visible light photodiode 206 and theat least one 3D photodiode 208 can be isolated from one another using avariety of trench isolation 212 or other techniques to lower oreliminate optical and/or electrical crosstalk between the photodiodes.In some aspects, the trench isolation itself can be textured and/ordoped as discussed herein. Additionally, the trench isolation can befilled with an oxide material. It is noted that each of the variousphotodiodes can have multiple doped regions forming at least onejunction. In some aspects, doped regions can include an n-type dopantand/or a p-type dopant, thereby creating a p-n junction. In otheraspects, a photosensitive device can include an i-type region to form ap-i-n junction. Various dopants and dopant profiles are discussedfurther herein.

In another aspect, a photodiode can include an electrical transferelement coupled to the semiconductor substrate and operable to transferan electrical signal from the junction. Non-limiting examples ofelectrical transfer elements can include a variety of devices such astransistors, transfer gates, MOSFETs, PMOS transfer gates, and the like.

In general, a photodiode can include passive pixel sensors (PPS), activepixel sensors (APS), digital pixel sensor imagers (DPS), or the like,with one difference being the image sensor read out architecture. Forexample, a semiconducting photodiode can be a three, four, five or sixtransistor active pixel sensor (3T, 4T, 5T, or 6T APS). Devices havinggreater than 6 transistors are also within the present scope.

In another aspect of the present disclosure, a 3D optoelectronic deviceis provided. Such a device can include a semiconductor substrate havinga device surface, at least one 3D photodiode formed at the devicesurface, and a quantum efficiency enhanced infrared light regionfunctionally coupled to the at least one 3D photodiode and positioned tointeract with electromagnetic radiation.

Regarding the layout of a monolithic sensor or monolithic sensor array,a variety of configurations are considered. It should be noted thatnumerous combinations of visible light photodiodes (or pixels) and 3Dphotodiodes (or pixels) are possible, and any such combination isconsidered to be within the present scope. For example, FIG. 3 shows inone aspect a basic pixel array arrangement that is similar to a “Bayer”pattern found in color sensors. A Bayer pattern typically has a redpixel, a blue pixel, and two green pixels located in opposite corners ofthe pattern. As can be seen in FIG. 3, a similar layout can include oneblue pixel 302, one red pixel 304, one green pixel 306, and one 3D pixel308. FIG. 4 shows an arrangement with one blue pixel 402, one red pixel404, one green pixel 406, and two 3D pixel 408, 410 (3D TOF_1, and 3DTOF_2). Having multiple 3D pixels, such as the combination of two 3Dpixels, can allows for better depth perception. In some aspects, thearrangements in FIGS. 3 and 4 can be beneficial for large pixel designs.

In another aspect, as shown in FIG. 5, the pixel arrangement includesseveral Bayer-type pattern imagers and two sets of 3D TOF pixels.Essentially, one TOF pixel replaces one quadrant of a RGGB pixel design.In this configuration, the addition of several green pixels allows forthe capture of more green wavelengths that may be needed for green colorsensitivity, while at the same time capturing the infrared light fordepth perception. In yet another aspect, FIG. 6 shows another possiblearrangement of color pixels and 3D pixels according. The pixelarrangements in FIGS. 5 and 6 can be beneficial for, among other things,small pixel sizes. It should be noted that other arrangements areconsidered within the scope of the present disclosure.

A monolithic 3D sensor can be operated according to a variety ofdifferent schemes and architectures, and as such, the present scopeshould not be limited by the schemes and architectures described. Forexample, FIG. 7 shows schematically one potential operating scheme of amonolithic photosensitive 3D imager or 3D sensor according to oneaspect. For a single 3D photodiode, the total integration time isdivided into two alternate portions. Integration 1 is synchronized withthe drive signal from the infrared light source, such as an LED.Integration 2 is opposite the drive signal of the LED. The signal of thereceived light can be split between integration 1 and integration 2. Theintegration cycle can be repeated several times before the accumulatedsignals are read out. The ratio between S1 and S2 can be used to derivethe phase shift of received light relative to the emitted light as shownby Equations II, III, and IV:

$\begin{matrix}{{S\; 1} = {{\sum\limits_{1}^{N}\; {S\; 1_{i}}} = {{S\; 1_{LED}} + {S\; 0}}}} & {II} \\{{S\; 2} = {{\sum\limits_{1}^{N}\; {S\; 2{\_ i}}} = {{S\; 2{\_ LED}} + {S\; 0}}}} & {III} \\{{d = {\frac{c}{2}*\left\lbrack {{\frac{Tw}{4}\frac{2\; S\; 2_{LED}}{{S\; 1_{LED}} + {S\; 2_{LED}}}} + {n\left( \frac{Tw}{2} \right)}} \right\rbrack}},{{{where}\mspace{14mu} n} = 0},1,2,\ldots} & {IV}\end{matrix}$

Where d is the distance to the object, Tw is the period of the LEDmodulation (in seconds, e.g. in Tw=1/f, f is the modulation frequency),S1_LED and S2_led are signal levels caused by LED illumination, and c isthe speed of light. In the above equation, the integer number representsthe aliasing factor (e.g. ambiguity). S0 is the offset signal caused byambient light and dark current of the pixel. The offset signal can besubtracted from the total signal to accurately derive the distance. Theoffset depends on the ambient light and ambient temperature at eachlocation of the target (e.g. dark current). To derive the phase shiftinformation, the offset must be known.

Known TOF methods can have accuracy issues (e.g. ambiguity issues). Forexample, the ambiguity distance value is cTw/4, which can be derivedfrom the above equations. Thus, the derived phase shift of an object ata distance d is same as an object at a distance of d+n(cTw/4), wheren=0, 1, 2 . . . . To resolve this issue, multiple LED modulationfrequencies can be used to reduce ambiguity. In another aspect, themeasurement can be limited to a distance of less than cTw/4 to avoidambiguity.

Photosensitive imagers can be front side illumination (FSI) or back sideillumination (BSI) devices. In a typical FSI imager, incident lightenters the semiconductor device by first passing by transistors andmetal circuitry. The light, however, scatters off of the transistors andcircuitry prior to entering the light sensing portion of the imager,thus causing optical loss and noise. A lens can be disposed on thetopside of a FSI pixel to direct and focus the incident light to thelight sensing active region of the device, thus partially avoiding thecircuitry. BSI imagers, one the other hand, are configured to have thelight sensing portion of the device opposite the circuitry. Incidentlight enters the device via the light sensing portion and is mostlyabsorbed prior to reaching the circuitry. BSI designs allow for smallerpixel architecture and a high fill factor for the imager. As mentioned,the devices according to aspects of the present disclosure can beadapted for either configuration. It should also be understood thatdevices according to aspects of the present disclosure can beincorporated into complimentary metal-oxide-semiconductor (CMOS) imagerarchitectures or charge-coupled device (CCD) imager architectures.

One example of a monolithic 3D sensor is shown in FIG. 8, whichillustrates a cross-sectional view of both a visible photodiode on theright and a 3D photodiode on the left. Both the visible and 3Dphotodiodes are designed in a BSI architecture. The BSI architecture canalso be useful due to having improved QE response in the visiblespectrum. The monolithic 3D sensor can include a carrier wafer 802, adielectric layer 804, circuitry layers 806, 808 and 810, via(s) 812, anda transfer gate 814. The monolithic 3D sensor can further include afirst doped region 816 (e.g. for this embodiment, p+), a second dopedregion 818 (e.g. for this embodiment, n-type), a semiconductor layer820, a isolation feature 822, an anti-reflective layer 824, infraredfilter and a lens 826 for focusing incident electromagnetic radiation.Furthermore, the 3D photodiode can have a quantum efficiency enhancedinfrared light region 828. In some aspects, the visible light photodiodecan also include a quantum efficiency enhanced infrared light region(not shown).

The 3D photodiode can also include an on-pixel optical narrow passfilter 832. The narrow pass filter design will match the modulated lightsource (e.g. LED or laser) emission spectrum. The narrow pass filterwill significantly reduce the unwanted ambient light which will furtherincrease the SNR of modulated NIR light. Another benefit of increasedNIR QE is possibility of high frame rate operation for high speed 3Dimage capture. The visible pixel will have on-pixel color filter array(CFA) and IR cut filter. The integrated IR cut filter can allow highquality visible images with high fidelity color rendering. Byintegrating an infrared cut filter onto the sensor chip can also reducetotal system costs (due to, for example, the removal infrared filterglass) and can reduce module profile. It is noted that the 3D photodiodecan have a light absorbing properties and elements as has been disclosedin U.S. patent application Ser. No. 12/885,158, filed on Sep. 17, 2010,which is incorporated by reference in its entirety.

The photodiode (pixel) configured for detecting visible wavelengths caninclude the same elements as the 3D photodiode with the exception ofhaving a color filter array (CFA) and an infrared cut filter 830.Notably, both the narrow pass NIR filter and IR cut filter can be madeby a variety of multiple-layer interference type schemes. The on chippixel level optical filter will allow high quality images for both thedepth map and the color image.

As has been described, the various photodiodes can have any number oftransistors and transistor architectures. In one aspect, for example,the visible pixel can have a six-transistor (6-T) architecture that willallow global shutter operation. One example of such a 6-T architectureis shown in FIG. 9. This pixel architecture can include a photodiode(PD) 902, a global reset (Global_RST) 904, a global transfer gate(Global_TX) 906, a storage node 908, a transfer gate (TX1) 910, reset(RST) 912, source follower (SF) 914, floating diffusion (FD) 916, rowselect transistor (RS) 918, power supply (Vaapix) 920, and voltage out(Vout) 922. Due to the use of an extra transfer gate and storage node,correlated-double-sampling (CDS) is allowed. Therefore, the read noiseshould be similar to a typical CMOS 4T pixel.

One example global shutter timing for short integration is shown in FIG.10. In global shuttering, the Global_RST can be maintained at a highstate for anti-blooming purposes. The Global_RST is set to a low state(or off) to begin integration of the pixel array. At the end ofintegration, Global_TX is pulsed to transfer the integrated charge fromthe photodiode 902 to the Storage Node 908 (FIG. 9) for each pixel inthe array. After charge transfer, the Global_RST signal can be set to ahigh state again during the frame readout for anti-blooming purposes.The readout of each row can occur similar to a 4T pixel operation. Thefloating diffusion (FD) node 916 can be reset for sampling before thesignal charge is transferred from the Storage Node. The function ofcorrelated double sampling can then result in low read noise. Moreinformation regarding anti-blooming, global shuttering, correlateddouble sampling, and the like, can be found in U.S. patent Ser. No.13/333,537, filed on Dec. 21, 2011, which is incorporated herein byreference.

In another aspect, a schematic of a 3D pixel is shown in FIG. 11. Thisexemplary 3D pixel can include 11 transistors for accomplishing thedepth measurement of the target. It should be noted that 11 transistorsshould not be seen as limiting, and other transistor architectures arecontemplated. In this aspect, however, the 3D pixel can comprise aphotodiode (PD) 1102, a global reset (Global_RST) 1104, a first globaltransfer gate (Global_TX1) 1106, a first storage node 1108, a firsttransfer gate (TX1) 1110, a first reset (RST1) 1112, a first sourcefollower (SF1) 1114, a first floating diffusion (FD1) 1116, a first rowselect transistor (RS1) 1118, a second global transfer gate (Global_TX2)1120, a second storage node 1122, a second transfer gate (TX2) 1124, asecond reset (RST2) 1126, a second source follower (SF2) 1128, a secondfloating diffusion (FD2) 1130, a second row select transistor (RS2)1132, power supply (Vaapix) 1134, and voltage out (Vout) 1136. Othertransistors can be included in the 3D architecture and should beconsidered within the scope of the present disclosure. The specificaspect with 11 transistors can reduce motion artifacts due to the globalshutter operation, thereby giving more accurate measurements.

The timing of a 3D pixel can be performed in a variety of ways, and assuch, the following timing diagrams and description should not be seenas limiting, but merely exemplary methods of achieving a desired result.An exemplary timing diagram corresponding to the timing of the schematicof FIG. 11 is shown in FIG. 12. FIG. 12 shows the output of an 850 nmLED on a 50% duty cycle. The Global_RST is pulsed at the beginning andend of each LED cycle to reset the photodiode. Thus, as the LED isturned on the photodiode is reset and integration begins. Global_TX1 ispulsed at the end of the LED on phase to transfer the accumulated chargeinto Storage 1 and the photodiode is reset. Global_TX2 is pulsed at theend of the LED off cycle to transfer accumulated charge from thephotodiode into Storage 2. Following a desired number of integrationcycles, the charge in Storage 1 and Storage 2 are transferred to FD1 andFD2, read out using a global shutter mode, and compared to determinedistance information.

In addition, the background infrared level can introduce errors into thedistance measurement. This background signal can be measured andsubtracted from the actual signal to provide a more accuratedetermination of distance. A timing diagram of one technique for makingsuch a background measurement is shown in FIG. 13. The timing as shownin FIG. 12 is thus performed with the LED off, and the resultingbackground signal can be subtracted from the signal derived with the LEDon to improve the distance measurement. The background measurement canbe performed at any time with relation to the actual distancemeasurement. For example, in one aspect, the background measurement canbe performed in between each global readout cycle. In another aspect,the background measurement can be performed at given time intervals,such as every second, every, 10 seconds, every 30 seconds, every minute,etc. Such a background reading can be taken whenever it is desirable tocheck the background infrared levels to improve sensor performance.

The present disclosure additionally provides systems for detectinginfrared and visible light. In one aspect, as is shown in FIG. 14 forexample, such a system can include a monolithic 3D sensor 1402 fordetecting infrared and visible light, comprising a semiconductorsubstrate 1404 having a device surface 1406, at least one visible lightphotodiode 1408 formed at the device surface, at least one 3D photodiode1410 formed at the device surface in proximity to the at least onevisible light photodiode, and a quantum efficiency enhanced infraredlight region 1412 functionally coupled to the at least one 3D photodiodeand positioned to interact with electromagnetic radiation. The systemcan further include an infrared light source 1414 operable to emitinfrared light 1416 detectable by the 3D photodiode, and synchronizationcircuitry 1418 between the infrared light source and the 3D photodiodeto synchronize detection of infrared light 3D photodiode with a pulse ofthe infrared light source.

The various devices according to aspects of the present disclosureexhibit increase quantum efficiencies (QE) as compared to traditionalphotodiode devices. On example of the QE improvements of such devicescan be seen in the QE spectrum curve in FIG. 15. The curve in FIG. 15shows a standard imager and an imager with enhanced quantum efficiency,especially in the infrared wavelengths. The QE enhanced imager and thestandard imager both have comparable silicon thicknesses of about 5 μm.The thickness and responsivity of the QE enhanced imager can havesignificant impact on a 3D pixel operation, due to increased speed anddetection. The increased QE can contribute to higher image signal tonoise ratio (SNR), which will greatly reduce depth error. Further,increased QE on a silicon having a thickness of less than 5 μm can allowthe pixel to reduce the diffusion component of the signal so that thecharge collection and transfer can be increased, which is ideal for 3Dpixel operation. In general, the photo-generated carriers created insidethe pixel will depend on two mechanisms for collection: drift anddiffusion. For light having shorter wavelengths, most of the carrierswill be generated in a shallow region of the device and within thedepletion region of the photodiode. Those carriers can be collectedrelatively quickly, via drift. For infrared light, however, the majorityof photo carriers will be generated toward the backside of the silicon.These carriers will thus be generated outside diode's depletion regionand will depend on diffusion to be collected. Diffusion is much slowerthan drift. For a 3D TOF pixel, fast sampling of photo charge isbeneficial. High QE can be achieved within very thin (i.e. less than 5μm) layers of epitaxially grown silicon using the techniques of thepresent disclosure. Therefore, most if not all carriers generated can becollected via the drift mechanism. This allows very fast chargecollection and transfer. With this technology, depth resolution can begreatly increased due to the use of higher modulation frequencies offaster modulated infrared LEDs.

Photosensitive imagers can be maintained under constant conditions(fixed voltage or current) to provide enhanced linearity and uniformity.As has been described, connections between the imager and the devicelayers can be achieved using vias fabricated from a refractory metal,such as tungsten or tantalum. Placing storage elements under the imagermay also provide various photonic benefits. For example, the entirepixel array may be dedicated to signal processing. This may enablehigher performance by permitting access to low level pixel signals.Furthermore, massively parallel operations can be performed by pixelprocessors. For example, analog to digital conversion, noise reduction(i.e., true correlated double sampling), power conditioning, nearestneighbor pixel processing, compression, fusion, and color multiplexingoperations can be performed.

Regarding the photodiodes themselves, a variety of semiconductormaterials are contemplated for use with such devices. Non-limitingexamples of such semiconductor materials can include group IV materials,compounds and alloys comprised of materials from groups II and VI,compounds and alloys comprised of materials from groups III and V, andcombinations thereof. More specifically, exemplary group IV materialscan include silicon, carbon (e.g. diamond), germanium, and combinationsthereof. Various exemplary combinations of group IV materials caninclude silicon carbide (SiC) and silicon germanium (SiGe). In onespecific aspect, the semiconductor material can be or include silicon.Exemplary silicon materials can include amorphous silicon (a-Si),microcrystalline silicon, multicrystalline silicon, and monocrystallinesilicon, as well as other crystal types. In another aspect, thesemiconductor material can include at least one of silicon, carbon,germanium, aluminum nitride, gallium nitride, indium gallium arsenide,aluminum gallium arsenide, and combinations thereof.

Exemplary combinations of group II-VI materials can include cadmiumselenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zincoxide (ZnO), zinc selenide (ZnSe), zinc sulfide (ZnS), zinc telluride(ZnTe), cadmium zinc telluride (CdZnTe, CZT), mercury cadmium telluride(HgCdTe), mercury zinc telluride (HgZnTe), mercury zinc selenide(HgZnSe), and combinations thereof.

Exemplary combinations of group III-V materials can include aluminumantimonide (AlSb), aluminum arsenide (AlAs), aluminum nitride (AlN),aluminum phosphide (AlP), boron nitride (BN), boron phosphide (BP),boron arsenide (BAs), gallium antimonide (GaSb), gallium arsenide(GaAs), gallium nitride (GaN), gallium phosphide (GaP), indiumantimonide (InSb), indium arsenide (InAs), indium nitride (InN), indiumphosphide (InP), aluminum gallium arsenide (AlGaAs, AlxGa1−xAs), indiumgallium arsenide (InGaAs, InxGa1−xAs), indium gallium phosphide (InGaP),aluminum indium arsenide (AlInAs), aluminum indium antimonide (AlInSb),gallium arsenide nitride (GaAsN), gallium arsenide phosphide (GaAsP),aluminum gallium nitride (AlGaN), aluminum gallium phosphide (AlGaP),indium gallium nitride (InGaN), indium arsenide antimonide (InAsSb),indium gallium antimonide (InGaSb), aluminum gallium indium phosphide(AlGaInP), aluminum gallium arsenide phosphide (AlGaAsP), indium galliumarsenide phosphide (InGaAsP), aluminum indium arsenide phosphide(AlInAsP), aluminum gallium arsenide nitride (AlGaAsN), indium galliumarsenide nitride (InGaAsN), indium aluminum arsenide nitride (InAlAsN),gallium arsenide antimonide nitride (GaAsSbN), gallium indium nitridearsenide antimonide (GaInAsSb), gallium indium arsenide antimonidephosphide (GaInAsSbP), and combinations thereof.

Furthermore, the semiconductor device layer can be of any thickness thatallows electromagnetic radiation detection and conversion functionality,and thus any such thickness of semiconductor device layer is consideredto be within the present scope. In some aspects a textured region can beapplied to the semiconductor device layer to increase the efficiency ofthe device such that the semiconductor device layer can be thinner thanhas previously been possible. Decreasing the thickness of thesemiconductor reduces the amount of the often costly semiconductormaterial required to make such a device. In one aspect, for example, thesemiconductor device layer has a thickness of from about 500 nm to about50 μm. In another aspect, the semiconductor device layer has a thicknessof less than or equal to about 500 μm. In yet another aspect, thesemiconductor device layer has a thickness of from about 2 μm to about10 μm. In a further aspect, the semiconductor device layer can have athickness of from about 5 μm to about 750 μm. In yet a further aspect,the semiconductor device layer can have a thickness of from about 5 μmto about 100 μm. In other aspects, the semiconductor device layer canhave a thickness of from about 2 μm to about 5 μm.

One effective method of producing a textured region (i.e. quantumefficiency enhanced infrared light region) is though laser processing.Such laser processing allows discrete locations of the semiconductorsubstrate to be textured. A variety of techniques of laser processing toform a textured region are contemplated, and any technique capable offorming such a region should be considered to be within the presentscope. Laser treatment or processing can allow, among other things,enhanced absorption properties and thus increased electromagneticradiation focusing and detection. The laser treated region can beassociated with the surface nearest the impinging electromagneticradiation, or the laser treated surface can be associated with a surfaceopposite in relation to impinging electromagnetic radiation, therebyallowing the radiation to pass through the semiconductor material beforeit hits the laser treated region.

In one aspect, for example, a target region of the semiconductormaterial can be irradiated with laser radiation to form a texturedregion. Examples of such processing have been described in furtherdetail in U.S. Pat. Nos. 7,057,256, 7,354,792 and 7,442,629, which areincorporated herein by reference in their entireties. Briefly, a surfaceof a semiconductor material is irradiated with laser radiation to form atextured or surface modified region. Such laser processing can occurwith or without a dopant material. In those aspects whereby a dopant isused, the laser can be directed through a dopant carrier and onto thesemiconductor surface. In this way, dopant from the dopant carrier isintroduced into the target region of the semiconductor material. Such aregion incorporated into a semiconductor material can have variousbenefits in accordance with aspects of the present disclosure. Forexample, the target region typically has a textured surface thatincreases the surface area of the laser treated region and increases theprobability of radiation absorption via the mechanisms described herein.In one aspect, such a target region is a substantially textured surfaceincluding micron-sized and/or nano-sized surface features that have beengenerated by the laser texturing. In another aspect, irradiating thesurface of semiconductor material includes exposing the laser radiationto a dopant such that irradiation incorporates the dopant into thesemiconductor. Various dopant materials are known in the art, and arediscussed in more detail herein.

Thus the surface of the semiconductor material is chemically and/orstructurally altered by the laser treatment, which may, in some aspects,result in the formation of surface features appearing as microstructuresor patterned areas on the surface and, if a dopant is used, theincorporation of such dopants into the semiconductor material. In someaspects, the surface features or microstructures can be on the order of5 nm to 500 μm in size and can assist in the absorption ofelectromagnetic radiation. In other words, the textured surface canincrease the probability of incident radiation being absorbed by thesemiconductor material. In another aspect, the surface features can befrom about 10 nm to about 20 μm in size.

The type of laser radiation used to surface modify a semiconductormaterial can vary depending on the material and the intendedmodification. Any laser radiation known in the art can be used with thedevices and methods of the present disclosure. There are a number oflaser characteristics, however, that can affect the surface modificationprocess and/or the resulting product including, but not limited to thewavelength of the laser radiation, pulse width, pulse fluence, pulsefrequency, polarization, laser propagation direction relative to thesemiconductor material, etc. In one aspect, a laser can be configured toprovide pulsatile lasing of a semiconductor material. A short-pulsedlaser is one capable of producing femtosecond or picosecond pulsedurations. Laser pulses can have a central wavelength in a range ofabout from about 10 nm to about 8 μm, and more specifically from about200 nm to about 1200 nm. The pulse width of the laser radiation can bein a range of from about tens of femtoseconds to about hundreds ofnanoseconds. In one aspect, laser pulse widths can be in the range offrom about 50 femtoseconds to about 50 picoseconds. In another aspect,laser pulse widths are in the range of from about 50 femtoseconds to 500femtoseconds.

The number of laser pulses irradiating a target region can be in a rangeof from about 1 to about 2000. In one aspect, the number of laser pulsesirradiating a semiconductor target region can be from about 2 to about1000. Further, the repetition rate or frequency of the pulses can beselected to be in a range of from about 10 Hz to about 10 μHz, or in arange of from about 1 kHz to about 1 MHz, or in a range from about 10 Hzto about 1 kHz. Moreover, the fluence of each laser pulse can be in arange of from about 1 kJ/m² to about 20 kJ/m², or in a range of fromabout 3 kJ/m² to about 8 kJ/m².

It should be noted that other techniques for texturing the quantumefficiency enhanced infrared light region are considered to be withinthe present scope. Non-limiting examples include chemical etching,physical abrasion, material deposition, and the like.

A variety of dopant materials are contemplated, and any such materialthat can be used in the laser treatment process to surface modify asemiconductor material according to aspects of the present disclosure isconsidered to be within the present scope. It should be noted that theparticular dopant utilized can vary depending on the semiconductormaterial being laser treated, as well as the intended use of theresulting semiconductor material. For example, the selection ofpotential dopants may differ depending on whether or not tuning of thephotosensitive device is desired. Additionally, such dopant can beutilized in the textured region or in the other various doped regions ofthe device.

A dopant can be either electron donating or hole donating. In oneaspect, non-limiting examples of dopant materials can include S, F, B,P, N, As, Se, Te, Ge, Ar, Ga, In, Sb, and combinations thereof. Itshould be noted that the scope of dopant materials should include, notonly the dopant materials themselves, but also materials in forms thatdeliver such dopants (i.e. dopant carriers). For example, S dopantmaterials includes not only S, but also any material capable being usedto dope S into the target region, such as, for example, H₂S, SF₆, SO₂,and the like, including combinations thereof. In one specific aspect,the dopant can be S. Sulfur can be present at an ion dosage level ofbetween about 5×10¹⁴ and about 1×10¹⁶ ions/cm². Non-limiting examples offluorine-containing compounds can include ClF₃, PF₅, F₂SF₆, BF₃, GeF₄,WF₆, SiF₄, HF, CF₄, CHF₃, CH₂F₂, CH₃F, C₂F₆, C₂HF₅, C₃F₈, C₄F₈, NF₃, andthe like, including combinations thereof. Non-limiting examples ofboron-containing compounds can include B(CH₃)₃, BF₃, BCl₃, BN, C₂B₁₀H₁₂,borosilica, B₂H₆, and the like, including combinations thereof.Non-limiting examples of phosphorous-containing compounds can includePF₅, PH₃, and the like, including combinations thereof. Non-limitingexamples of chlorine-containing compounds can include Cl₂, SiH₂Cl₂, HCl,SiCl₄, and the like, including combinations thereof. Dopants can alsoinclude arsenic-containing compounds such as AsH₃ and the like, as wellas antimony-containing compounds. Additionally, dopant materials caninclude mixtures or combinations across dopant groups, i.e. asulfur-containing compound mixed with a chlorine-containing compound. Inone aspect, the dopant material can have a density that is greater thanair. In one specific aspect, the dopant material can include Se, H₂S,SF₆, or mixtures thereof. In yet another specific aspect, the dopant canbe SF₆ and can have a predetermined concentration range of about5.0×10⁻⁸ mol/cm³ to about 5.0×10⁻⁴ mol/cm³. SF₆ gas is a good carrierfor the incorporation of sulfur into the semiconductor material via alaser process without significant adverse effects on the semiconductormaterial. Additionally, it is noted that dopants can also be liquidsolutions of n-type or p-type dopant materials dissolved in a solutionsuch as water, alcohol, or an acid or basic solution. Dopants can alsobe solid materials applied as a powder or as a suspension dried onto thewafer.

Additionally, the semiconductor device layer can be annealed for avariety of reasons, including dopant activation, semiconductor materialrepair, and the like. In those aspects including a laser texturedregion, the semiconductor material can be annealed prior to lasertreatment, following laser treatment, during laser treatment, or bothprior to and following laser treatment. Annealing can enhance thesemiconductive properties of the device, including increasing thephotoresponse properties of the semiconductor materials. Additionally,annealing can reduce damage done by the lasing process.

Of course, it is to be understood that the above-described arrangementsare only illustrative of the application of the principles of thepresent disclosure. Numerous modifications and alternative arrangementsmay be devised by those skilled in the art without departing from thespirit and scope of the present disclosure and the appended claims areintended to cover such modifications and arrangements. Thus, while thepresent disclosure has been described above with particularity anddetail in connection with what is presently deemed to be the mostpractical embodiments of the disclosure, it will be apparent to those ofordinary skill in the art that numerous modifications, including, butnot limited to, variations in size, materials, shape, form, function andmanner of operation, assembly and use may be made without departing fromthe principles and concepts set forth herein.

1. A monolithic 3D sensor capable of detecting infrared and visiblelight, comprising: a semiconductor substrate having a device surface; atleast one visible light photodiode formed at the device surface; atleast one 3D photodiode formed at the device surface in proximity to theat least one visible light photodiode; and a quantum efficiency enhancedinfrared light region functionally coupled to the at least one 3Dphotodiode and positioned to interact with electromagnetic radiation. 2.The sensor of claim 1, wherein the quantum efficiency enhanced infraredlight region is a textured region located at the device surface.
 3. Thesensor of claim 1, wherein the quantum efficiency enhanced infraredlight region is a textured region located on a side of the semiconductorsubstrate opposite the device surface.
 4. The sensor of claim 1, whereinthe quantum efficiency enhanced infrared light region has surfacestructures formed using a pulsed laser with a pulse duration of fromabout 1 femtosecond to about 500 picoseconds.
 5. The sensor of claim 4,wherein the surface structures have an average height of from about 5 nmto about 500 μm
 6. The sensor of claim 1, wherein the at least onevisible light photodiode includes at least one red light-sensitivephotodiode, at least one blue light-sensitive photodiode, at least onegreen light-sensitive photodiode, and at least one 3D photodiode.
 7. Thesensor of claim 1, wherein the 3D photodiode is operable to detectinfrared light having a wavelength of greater than about 800 nm.
 8. Thesensor of claim 1, further comprising an infrared narrow bandpass filteroptically coupled to the 3D photodiode and positioned to filterelectromagnetic radiation impinging on the 3D photodiode.
 9. The sensorof claim 1, further comprising an infrared cut filter optically coupledto the at least one visible light diode and positioned to filterinfrared electromagnetic radiation impinging on the at least one visiblelight photodiode.
 10. The sensor of claim 1, wherein the 3D photodiodefurther includes circuitry for capturing signals generated by the 3Dphotodiode in response to detection of a pulse of infrared light from aninfrared light source.
 11. The sensor of claim 1, wherein the 3Dphotodiode further includes circuitry for calculating time of flightinformation.
 12. The sensor of claim 1, further comprising circuitry forsynchronizing light capture of the 3D photodiode with an infrared lightsource.
 13. The sensor of claim 1, further comprising readout circuitryfunctionally coupled to the at least one visible light photodiode andthe at least one 3D photodiode operable to function in global shuttermode.
 14. The sensor of claim 1, wherein the sensor is configured as abackside illuminated sensor.
 15. A system for detecting infrared andvisible light, comprising: a monolithic 3D sensor for detecting infraredand visible light, comprising: a semiconductor substrate having a devicesurface; at least one visible light photodiode formed at the devicesurface; at least one 3D photodiode formed at the device surface inproximity to the at least one visible light photodiode; and a quantumefficiency enhanced infrared light region functionally coupled to the atleast one 3D photodiode and positioned to interact with electromagneticradiation; an infrared light source operable to emit infrared lightdetectable by the 3D photodiode; and synchronization circuitry betweenthe infrared light source and the 3D photodiode to synchronize detectionof infrared light 3D photodiode with a pulse of the infrared lightsource.
 16. The system of claim 15, wherein the quantum efficiencyenhanced infrared light region is a textured region located at thedevice surface.
 17. The system of claim 15, wherein the quantumefficiency enhanced infrared light region has surface structures formedusing a pulsed laser with a pulse duration of from about 1 femtosecondto about 500 picoseconds.
 18. The system of claim 17, wherein thesurface structures have an average height of from about 5 nm to about500 μm.
 19. The system of claim 15, wherein the at least one visiblelight photodiode includes at least one red light-sensitive photodiode,at least one blue light-sensitive photodiode, at least one greenlight-sensitive photodiode, and at least two 3D photodiodes.
 20. Thesystem of claim 15, wherein the 3D photodiode is operable to detect theinfrared light from the infrared light source.
 21. The system of claim20, further comprising an infrared narrow bandpass filter opticallycoupled to the 3D photodiode and positioned to filter electromagneticradiation impinging on the 3D photodiode, wherein the infrared narrowbandpass filter has a pass band substantially matching the infraredlight frequency.
 22. The system of claim 15, further comprising aninfrared cut filter optically coupled to the at least one visible lightdiode and positioned to filter infrared electromagnetic radiationimpinging on the at least one visible light photodiode.
 23. The systemof claim 15, wherein the 3D photodiode further includes circuitry forcapturing signals generated by the 3D photodiode in response todetection of a pulse of the infrared light from the infrared lightsource.
 24. The system of claim 15, further comprising circuitry forsynchronizing light capture of the 3D photodiode with the infrared lightgenerated by the infrared light source.